Thanks for the advice. I'll try the blower and graduate to the cleaner should the blower not work.
UPDATE APRIL 1, 2008....
So, for anyone reading this thread or with similar problems, I'll post the results of my effort fix this issue...
Following David's advice I first used a rocket blower to try and clean it up, which didn't work. I then graduated to a compressed air blower and throughly blew out the wheel and what not. This did improve performance of the wheel, however, there were still occasional problems, albeit much less frequently. So clearly the blowing did some good, just not enough.
Now my camera was really starting to aggravate me (nothing like spending $1500 on a camera and 4 months later you can't change any settings using the rear control dial without it going out of control). So I went out and bought some residue-free electronics cleaning spray, and went to town on the control dial. Again, following David's advice to apply it with "great care", I placed the straw of the can into the crack by the wheel (after removing the battery and CF card for good measure in case of disaster), and tried to gently direct the spray into the wheel. Well, the spray went everywhere, at full force, but most went into the wheel thankfully. I rotated the wheel around until the spray evaporated and then blew it out again with air. Repeated this twice.
So it's now been around two days and since the cleaning I haven't noticed any problems. So far so good, the control dial appears to be greatly improved, perhaps not 100%, but much much better. Hopefully this takes care of the issue for good, or worst case, till it needs another quick cleaning.
The only problem is that after the electronics spray seemed to work so well on the control dial, I tried to clean the mirror and the camera's sensor by giving each a quick spray with the solution, but now there seems to be some kind of white film on the sensor that won't rub off. ok, it was april fools day, so I made that last sentence up... :~)